Rotating member, housing, bearing, gearbox, rotating machine, shaft structure, and surface treatment method

ABSTRACT

In a rotation member ( 5 ) rotatably engaged with a housing ( 3 ), a pulsing electric discharge is generated in a processing liquid or in a gas, between an electrode and the rotation member ( 5 ). The electrode is a chemical compound from metallic powder or metal, or a molded body formed by molding ceramic powder, or a molded body obtained by heating the molded body. Energy of the electric discharges causes coating to be formed on an engagement portion ( 15 ) engaging the housing ( 3 ), the coating formed from the material of the electrode or a substance to which the electrode material combined by the energy of the electric discharges.

TECHNICAL FIELD

The present invention relates to a bearing for a rotation body, where,for example, a pulsing electric discharge is generated between a moldedbody molded from powder of metal compounds as an electrode and arotation member at an engaging portion between a housing of a gear boxand a rotation member of the gear box, and a coating of the electrodematerial is formed on the bearing by means of energy of the electricdischarges.

Moreover, for example, the present invention relates to a shaft for avariable stator which is provided in a compressor of a gas turbine, astructure of a shaft of a variable stator of a variable turbine nozzlein a turbo charger and a method for surface treatment thereof, and moreparticularly to a structure in which a shaft is provided with a coatinglayer having anti-abrasiveness and lubricity and a method for surfacetreatment thereof.

BACKGROUND ART

FIG. 6 is a cross sectional view showing a schematic constitution of aprior accessory drive gear box 200.

The accessory drive gear box 200 for driving equipments such as anelectric generator and a hydraulic pump is provided with a housing 202.

Moreover, a rotation axis member (a rotation member) 206 integrallyformed with a gear 204 is provided with interposing a roller bearing 208such as a cylindrical roller bearing so as to be rotatable with respectto the housing 202 (for example, “New Aeronautical Engineering, volume8, Jet Engine (Structure Part)”, published by Japan AeronauticalEngineers' Association, May 29, 2000, the 1st edition, the 6th printing,p99 FIG. 3-73). On the other hand, as a speed reducer and such, arotation member of which has greater revolution numbers than theaccessory drive gear box 200, there is known one using a fluid bearinginstead of the roller bearing.

Moreover, a compressor provided in a gas turbine is provided with avariable stator. When abrasion occurs at a shaft of the variable statorand a clearance therebetween comes to be greater, precision of adirection angle of the variable stator decreases, therefore the whole ofthe variable stator has to be detached and exchanged when the abrasionof the shaft comes to be great. Therefore, there is proposed aconstitution in which a detachable abrasive sleeve is provided on theshaft for protection of the shaft and a wore abrasive sleeve isexchanged to a new abrasive sleeve when the abrasive sleeve is greatlywore (for example, Japanese Patent Application Laid-open No.2000-329139).

Meanwhile, in the prior accessory drive gear box 200, since the bearingis composed of the roller bearing, there is a problem that the bearingis hard to be installed in a small space.

On the other hand, the fluid bearing has a problem that, if a film ofoil does not transiently exist, the housing and the rotation memberdirectly contact each other and hence durability of the bearing maydeteriorate.

The above problem may also occur to any gear box other than theaccessory drive gear box and further any bearing of a machine or adevice provided with a housing and a rotation member which is rotatablerelative to the housing (the bearing between the housing and therotation member).

Moreover, the constitution disclosed in the aforementioned patentpublication is a constitution as shown in FIG. 7 in which a shaftportion 147 of a variable stator detachably having an abrasive sleeve145 is fit into a cylindrical bush 143 fit in a hole provided in ahousing 141 and an antifriction layer 149 made of a material of lowfriction is provided between an outer periphery of the abrasive sleeve145 and an inner periphery of the bush 143.

In accordance with the aforementioned constitution, since the shaftportion 147 is protected by the abrasive sleeve 145, wear of the shaft147 maybe prevented, however, since the abrasive sleeve 145 is subjectto wear, the abrasive sleeve 145 needs to be detached and exchanged.More specifically, since the shaft portion 147 is prevented from wear,the whole of the variable stator is unnecessary to be exchanged,however, there is a problem that detachment and exchange of the abrasivesleeve 145 needs to be accomplished at relatively frequent intervals.

DISCLOSURE OF INVENTION

The present invention based on a first aspect is a rotation member,wherein, in a rotation member rotatably or swingably engaging with ahousing, a pulsing electric discharge is generated between a molded bodymolded from a metal powder or a mixture of powders of one or more ofmetal compounds or ceramics as an electrode or the molded body afterbeing processed with a heat treatment and the rotation member in aprocessing liquid or a gas, and a coating of the electrode material orany substance combined from the electrode material by energy of theelectric discharges is formed on an engaging portion engaging with thehousing by means of energy of the electric discharges.

The present invention based on a second aspect is a rotation member,wherein, in the rotation member recited in the first aspect, a groovefor pooling a lubrication liquid is formed on the engaging portion.

The present invention based on a third aspect is a rotation member,wherein, in the rotation member recited in the first aspect or thesecond aspect, the metal powder or the metal compounds or ceramics areTi, Si, cBN (cubic boron nitride), TiC (titanium carbide), WC (tungstencarbide), SiC (silicon carbide), Cr₃C₂ (chromium carbide), Al₂O₃(aluminum oxide; alumina), ZrO₂—Y (stabilized zirconium oxide;stabilized zirconia), TiN (titane nitride), TiB (titanium boride),hexagonal BN (boron nitride), MOS₂ (molybdenum disulfide), Cr₂O₃, WS₂(tungsten disulfide) and BaZrO₄ (barium zirconate).

The present invention based on a fourth aspect is a rotation member,wherein, in the rotation member recited in any of the first throughthird aspect, a coating is formed in the pulsing electric discharge withrotating the rotation member.

The present invention based on a fifth aspect is a housing, wherein, ina housing with which a rotation member rotatably or swingably engages, apulsing electric discharge is generated between a molded body moldedfrom a metal powder or a mixture of powders of one or more of metalcompounds or ceramics as an electrode or the molded body after beingprocessed with a heat treatment and the rotation member in a processingliquid or a gas, and a coating of the electrode material or anysubstance combined from the electrode material by energy of the electricdischarges is formed on an engaging portion engaging with the rotationmember by means of energy of the electric discharges.

The present invention based on a sixth aspect is a housing, wherein, inthe housing recited in the fifth aspect, a groove for pooling alubrication liquid is formed on the engaging portion.

The present invention based on a seventh aspect is a bearing for arotation member, wherein, in a bearing of a rotation member rotatablyengaging with a housing, a pulsing electric discharge is generatedbetween a molded body molded from a metal powder or a mixture of powdersof one or more of metal compounds or ceramics as an electrode or themolded body after being processed with a heat treatment and the rotationmember in a processing liquid or a gas, and a coating of the electrodematerial or any substance combined from the electrode material by energyof the electric discharges is formed on at least one of an engagingportion engaging with the housing and a engagement subject portion ofthe housing having a slightly larger inner diameter than an outerdiameter of the engaging portion and engaged with the engaging portion.

The present invention based on an eighth aspect is a bearing for arotation member, wherein, in the bearing for the rotation member recitedin the seventh aspect, a groove for pooling a lubrication liquid isformed on at least one of the engaging portion and the engagementsubject portion.

The present invention based on a ninth aspect is a gear box assembly,wherein, in a gear box driven by a turbine shaft of a gas turbine, thegear box assembly has a housing supported by an engine casing of the gasturbine at the exterior of the engine casing and a rotation memberprovided with an engaging portion engaging with a engagement subjectportion of the housing and provided to engage with the housing by theengaging portion so as to be rotatable relative to the housing in theinterior of the housing, and an inner diameter of the engagement subjectportion is formed slightly larger than an outer diameter of the engagingportion, and further a pulsing electric discharge is generated between amolded body molded from a metal powder or a mixture of powders of one ormore of metal compounds or ceramics as an electrode or the molded bodyafter being processed with a heat treatment and the rotation member in aprocessing liquid or a gas, and a coating of the electrode material orany substance combined from the electrode material by energy of theelectric discharges is formed on the engaging portion of the rotationmember by means of energy of the electric discharges, and a groove forpooling a lubrication liquid is formed on the engagement subject portionof the housing.

The present invention based on a tenth aspect is a rotating machine,wherein, in a rotating machine in which a rotation member is provided tobe rotatable in a casing with interposing a roller bearing, a coating isformed at a portion of the rotation member engaging with the rollerbearing and the coating is composed of an electrode material or anysubstance combined from an electrode material by energy of electricdischarges where the electric discharges are pulsingly generated betweena molded body molded from a metal powder or a mixture of powders of oneor more of metal compounds or ceramics as an electrode or the moldedbody after being processed with a heat treatment in a processing liquidor a gas.

The present invention based on an eleventh aspect is a shaft structurefor variable vanes for regulating a fluid, which is integrally providedwith a coating layer including ceramics or ceramics and a solidlubricant having anti-abrasiveness and lubricity on a peripheral surfaceof a shaft portion provided in the variable vanes for regulating thefluid.

The present invention based on a twelfth aspect is a shaft structure forvariable vanes for regulating a fluid, wherein, in the variable vanesfor regulating the fluid recited in the eleventh aspect, the ceramicsare ceramics including one or more of cBN, TiC, WC, SiC, Cr₃C₂, Al₂O₃,ZrO₂—Y, TiN, TiB, and the solid lubricant is a lubricant including oneor more of hexagonal BN, MOS₂, Cr₂O₃, WS₂ and BaZrO₄.

The present invention based on a thirteenth aspect is a shaft structurefor variable vanes for regulating a fluid, wherein, in the variablevanes for regulating the fluid recited in the eleventh aspect or thetwelfth aspect, the variable vanes for regulating the fluid is variablestator vanes provided in a compressor and/or a turbine in a gas turbineengine or a supercharger.

The present invention based on a fourteenth aspect is a method forsurface treatment of a shaft of variable vanes for regulating a fluid,which includes generating a pulsing electric discharge between anelectrode including ceramics such as cBN, TiC, WC, SiC, Cr₃C₂, Al₂O₃,ZrO₂—Y, TiN and TiB or containing these ceramics and a solid lubricantsuch as hexagonal BN, MoS₂, Cr₂O₃, WS₂ and BaZrO₄ and a shaft portion ofthe variable vanes for regulating the fluid, and forming a coating layercomposed of electrode constituents or compounds combined in an electricdischarge atmosphere having anti-abrasiveness and lubricity on a surfaceof the shaft portion.

The present invention based on a fifteenth aspect is a method forsurface treatment, wherein, in the method for the surface treatmentrecited in the fourteenth aspect, the coating layer is formed withrotating the shaft of the variable vanes for regulating the fluid.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A cross sectional view showing a schematic constitution of anaccessory drive gear box in accordance with an embodiment of the presentinvention.

FIG. 2 A view showing a IIA-IIB cross section in FIG. 1.

FIG. 3 An explanatory drawing for embodying the present invention asvariable vanes in a shaft portion of a variable stator provided in acompressor of a gas turbine engine.

FIG. 4 An explanatory drawing explaining a case of forming a coatinglayer having anti-abrasiveness and lubricity on the shaft of thevariable vanes.

FIG. 5 An explanatory drawing showing a constitution of the coatinglayer.

FIG. 6 A cross sectional view showing a schematic constitution of aprior accessory drive gear box.

FIG. 7 An explanatory drawing showing a constitution of a shaft portionof a variable stator.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 1 is a cross sectional view showing a schematic constitution of anaccessory drive gear box in accordance with an embodiment of the presentinvention and FIG. 2 is a view showing a IIA-IIB cross section in FIG.1.

An accessory drive gear box (it may be referred to as “gear box”hereinafter.) 1 is a gear box driven by a turbine shaft of a gas turbineand used for driving equipments (such as an electric generator and ahydraulic pump) of the gas turbine.

The accessory drive gear box 1 is provided with a housing 3, which issupported at the exterior of an engine casing of the gas turbine by theengine casing. Meanwhile, the engine casing is formed in a cylindricalshape so as to be provided with a compressor and a turbine in theinterior thereof and form a gas flow path.

A cylindrical rotation member 5 having electric conductivity is providedin the interior of the housing 3 so as to be rotatable with respect tothe housing 3. A gear 7 is integrally provided at a medium portion withrespect to a lengthwise direction of the rotation member 5. Respectivegears 9 and 11, which is provided integrally with the other rotationmembers (not shown) provided to be rotatable with respect to the housing3, engage with the gear 7. Meanwhile,

Further, the rotation member 5 is made to receive a rotational force ofthe turbine shaft of the gas turbine via the respective gears 9 and 7 soas to rotate. Meanwhile, not-shown equipments such as an electricgenerator and a hydraulic pump are coupled with the rotation member 5and rotation of the rotating member 5 makes the electric generatorgenerate electricity and the hydraulic pump generate hydraulic pressure.Moreover, the gear 7 and the gear 11 are capable of making the otherrotation members rotate.

At a side of one end portion for example with respect to the lengthwisedirection of the rotation member 5 (one end portion at the left side ofFIG. 1), an engaging portion 15 formed in a cylindrical side surface andengaged with a engagement subject portion (an opening of a cylindricalside surface shape) 13 of the housing 3 is provided. Further, byengaging at the engaging portion 15, the rotation member 5 is rotatablewith respect to the housing 3 in the interior of the housing 3.

An inner diameter D1 of the engagement subject portion 13 of the housing3 is formed to be slightly larger than an outer diameter D3 of theengaging portion 15 of the rotation member 5 and plural grooves 13A forpooling a lubricating liquid such as a lubricating oil are formed on asurface of the engagement subject portion 13 of the housing 3.

The respective grooves 13A are provided to be long in the lengthwisedirection of the rotation member 5 and disposed at positions equallydividing a circumference of the engagement subject portion 13 of thecylindrical side surface shape. Meanwhile, the respective grooves 13Amay be provided at the engaging portion 15 of the rotation member 5.

To the grooves 13A, the lubricating liquid such as the lubricating oilis supplied by a pump (now shown) driven by the rotational force of therotation member 5 for example and, by the supplied lubricating liquid, athin coating of the lubricating liquid is formed at a space (a narrowclearance) 17 between the engagement subject portion 13 of the housing 3and the engaging portion 15 of the rotation member 5 so as to form afluid bearing.

The supply of the lubricating liquid to the grooves 13A by the pump iscarried out by, for example, using a through hole (not shown) providedin the housing 3, one end portion of which is linked with the grooves13A and another end portion of which is linked with an electricdischarge port of the pump via a pipe (not shown) for supplying thelubricating liquid. Furthermore, the lubricating liquid supplied to thegrooves 13A returns to the interior of the housing 3 and is againsupplied to the grooves 13A by the pump.

Moreover, the housing 3 is provided with a hole 3A to engage with anouter peripheral portion 19A of a cylindrical bush 19 to support thebush 19. Further, by inserting the bush 19 into the hole 3A of thehousing 3 to be fixed, the engagement subject portion 13 of the housing3 is formed by an inner peripheral portion 19B of the bush 19.

As such constituted, machining of the engagement subject portion 13 toform the grooves 13A can be carried out with facility. Further, the bush19 is composed of a white metal or such and the housing 3 can becomposed of any material lower in price than the white metal, thereby aproduction cost of the gear box 1 can be reduced.

The rotation member 5 is provided with a flange 5A and one end face 5Bof the flange 5A is opposed to planar one end face 19C in the lengthwisedirection of the bush. Moreover, the end face 5B and the end face 19Care slightly separated so as to form a space (a narrow clearance) 21.

Further, because the lubricant liquid supplied to the grooves 13A by thepump passes through the space 21, the space 21 filled with the lubricantliquid forms a fluid bearing of the rotation member 5 in a thrustdirection. Therefore, the engagement subject portion 13 may be referredto as an engagement subject portion in a radial direction, the end face5B may be referred to as an engaging portion in the thrust direction andthe end face 19C may be referred to as an engagement subject portion inthe thrust direction.

Moreover, a fluid bearing similar to the left side is formed at anotherend portion in the lengthwise direction of the rotation member 5 (oneend portion at the right side of FIG. 1).

Next, a coating formed on the surface of the engaging portion 15 of therotation member 5 will be described.

On the surface of the engaging portion 15, the hard, or small in thecoefficient of friction, coating is formed.

The coating is formed by making a member formed by a molded body as anelectrode, making the electrode close to (for example in closeness about0.02 mm) the engaging portion 15 of the rotation member 5, generatingpulsing small electric discharges between the electrode and the engagingportion 15 of the rotation member 5 in a processing liquid or gas, andgradually depositing the electrode material on the engaging portion 15by means of its energy.

As the electrode, for example, a porous molded body molded from a powderincluding one or more ceramics (compounds of metal) such as cBN (cubicboron nitride), TiC (titanium carbide), WC (tungsten carbide), SiC(silicon carbide), Cr₃C₂ (chromiumcarbide), Al₂O₃ (aluminum oxide;alumina), ZrO₂—Y (stabilized zirconium oxide; stabilized zirconia), TiN(titane nitride), TiB (titanium boride) or containing these ceramics anda solid lubricant including one or more of solid lubricants such ashexagonal BN (boron nitride), MoS₂ (molybdenum disulfide), Cr₂O₃, WS₂(tungsten disulfide) and BaZrO₄ (barium zirconate) by, for example,compressing them is used. Alternatively, a molded body produced bycarrying out heat treatment with the aforementioned molded body in avacuum furnace is used. Therefore, the coating is formed from the samematerial as the electrode or any compound combined in the electricdischarge atmosphere.

Meanwhile, in a case where the electrode does not have electricconductivity, one uses what fine-powder-like metal and fine-powder-likeceramic are mixed and combined to form as an electrode for deposition.Alternatively, an electrode for deposition, which is formed fromfine-powder-like ceramic, surfaces of which is coated with a materialhaving electric conductivity, is used.

Alternatively, instead of the electrodes, one may compress and moldmetal powder such as Si(silicon) and Ti(titanium) and form an electrodefrom a compressed powder body which is formed from the compressed andmolded substance by heat treatment. More specifically, a porouselectrode formed by combining fine metal powder such as Si and Ti may beused. In this case, electric discharge is generated in a condition thatthe electrode and the engaging portion 15 of the rotation member 5exists in a processing liquid containing alkane hydrocarbons such askerosene and a coating of substances reacted by means of energy of theelectric discharge (for example, a substance composed of SiC or TiC) isformed on the surface of the engaging portion 15 of the rotation member5.

Furthermore, instead of compressing and molding, slurry pouring, MIM(Metal Injection Molding), spray forming (forming by spraying) and suchmay be applied to forming of the electrode.

Still furthermore, instead of the porous electrode formed by combiningfine metal powder of Si, an electrode formed of metallic Si (a crystalof Si without having any cavities therein) may be used.

In accordance with the gear box 1, in the bearing between the rotationmember 5 and the housing 3, a roller bearing is deleted and a fluidbearing is formed instead. Further, hard, or of low friction, coating isformed at the engaging portion 15 of the rotation member 5.

Moreover, because the coating is composed of deposited layers graduallyformed by reciprocally carrying out small welding by the electricdischarges, gradient alloy layers are formed in a thickness direction ofthe coating and cohesive strength between the coating and a main bodyportion of the rotation member 5 is hence strengthened, thereby thecoating is unlikely to peel off from the main body portion of therotation member 5.

Therefore, even if a film of the lubricant liquid between the engagingportion 15 of the rotation member 5 and the engagement subject portion13 of the housing 3 does not transiently exist for some reason, in otherwords, if the engaging portion 15 of the rotation member 5 and theengagement subject portion 13 of the housing 3 directly contact eachother, the bearing is unlikely to wear and further the bearing isinsusceptible to being broken by seizing and such and, as well, thebearing can be installed in a smaller space as compared with prior arts.

More specifically, in accordance with the bearing of the gear box 1, orin other words the fluid bearing between the rotating member 5 and thebush 19 (the housing 3), durability can be made higher as compared withthe prior fluid bearing and it can be installed in a smaller space (aspace smaller in a radial direction of the rotation member 5) ascompared with the prior roller bearing. Because of capability ofinstallation in a small space, a freedom of design at a time ofdesigning the bearing increases.

Therefore, it may be preferably applied to a gear box of a gas turbinefor an airplane, which requires space saving at a time of installation.

Moreover, because the roller bearing comes to be unnecessary,installation is made easier and the production cost can be reduced.

Moreover, if the lubricating liquid is forcibly supplied to a clearancebetween the engaging portion 15 of the rotation member 5 and theengagement subject portion 13 of the housing 3 by using the pump, thefilm of the lubricating liquid between the engaging portion 15 of therotation member 5 and the engagement subject portion 13 of the housing 3comes to be unlikely to be broken and hence the durability of thebearing is further improved.

Meanwhile, the engagement subject portion 13 and the grooves 13A maybedirectly, without using the bush 19, formed in the housing 3.

Further, the pump may be deleted to supply the lubricating liquid to thespace 17 between the engaging portion 15 and the engagement subjectportion 13 and to the space 21 by, for example, pooling an appropriateamount of the lubricating liquid in the housing 3 and stirring thelubricating liquid by the gear 7 of the rotation member 5.

Furthermore, instead of formation of the coating on the engaging portion15 of the rotation member 5, or in addition to formation of the coatingon the engaging portion 15 of the rotation member 5, the coating maybeformed on the engagement subject portion 13 of the housing 3. Meanwhile,in this case, the formation of the coating is carried out afterformation of the grooves 13A on the engagement subject portion 13 of thehousing 3.

Further, coatings from the electrode are preferably formed on the endface 5B and the end face 19C in the same way as the case of the engagingportion 15 and the engagement subject portion 13.

Moreover, the coatings may be formed porous. As so formed, the coatingsin themselves come to be capable of storing the lubricating liquid andhence any damages such as galling which may happen to the bearing cometo be unlikely to happen.

Further, the present embodiment may be applied to any gear boxes otherthan the accessory gear box and further applied to a bearing of amachine or a device provided with a housing and a rotation memberrotatable with respect to the housing (the bearing provided between thehousing and the rotation member).

By the way, the turbine of the gas turbine (the gas turbine engine) andthe rotation member of the rotating machine are rotatably provided inthe engine casing of the gas turbine with the interposed rollerbearings, coating from the electrode may be treated on surfaces ofregions of the rotation member of the rotating machine such as a turbineor a compressor of a gas turbine, where the inner ring of the rollerbearing engages. Meanwhile, in a case of a roller bearing which theinner ring does not exist, the coating may be formed on surfaces ofregions where the rollers and such of the roller bearing contacts.

As such, because the coating is formed on the regions where the innerrings and such of the roller bearing engages, any damages such asgalling in a case of installing the rotation member of the rotatingmachine such as the turbine and the compressor of the gas turbine andthe roller bearing and wear in a case of driving the gas turbine can beprevented.

Second Embodiment

In describing a second embodiment of the present invention by referringthe drawings, a case where the present invention is embodied in avariable stator in a compressor provided in a gas turbine will bedescribed. In an axial-flow compressor in a gas turbine, by changinginstallation angles of inflow guiding fins and upstream several stagesof stator vanes, regulation of angle of incidence relative to rotorblades into appropriate values as far as possible is in general carriedout.

Referring to FIG. 3, variable stator vanes (variable vanes) 101, aninstallation angle of which can be changed, are disposed in a ring-likeair flow path of the axial-flow compressor in the gas turbine among rowsof rotor blades (not shown) at even intervals (only one of them shown inFIG. 3) in a circumferential direction, and shaft portions 103 at outertip sides with respect to the variable stator vanes 101 are rotatablysupported by boss portions 107 of the casing 105 via bushes 109. Shaftportions 111 provided at inner tip sides of the variable stator vanes101 are swingably supported by boss portions 115 provided at circularbearing members 113, which enclose a rotor (not shown) provided with therotor blades in the axial-flow compressor.

As well, to swing the variable stator vanes 101 with respect to theshaft portions 103 and 111 as central axes, arms 117 which are long indirections perpendicular to the shaft portions 103 are installed to theshaft portions 103 at the outer tip sides and distal end sides of thearms 117 are pivotally connected with connection portions provided withring members (not shown) enclosing the casing 105.

Therefore, if the ring members are swung to the peripheral direction ofthe casing 105, the distal end sides of the arms 117 is moved to theperipheral direction. It leads to that the shaft portions 103 are swungaround axial centers and the installation angles are changed.

As mentioned above, repeating swings of the shaft portions 103 and 111so as to change the angle of the variable stator vanes 1 cause wear ofthe shaft portions 103 and 111 and thereby clearances around the shaftportions 103 and 111 gradually broaden. If the clearances come to bewide, detachment and exchange of the whole of the variable stator vanes101 are carried out because deviation of the regulation angle of thevariable stator vanes 101 occurs.

Thus, in accordance with the present embodiment, for suppression of wearof the shaft portions 103 and 111, outer peripheral surfaces of theshaft portions 103 and 111 are provided with coating layers 119 havinglubricity as well as anti-abrasiveness. The coating layers 119 are soconstituted as to contain ceramics such as cBN, TiC, WC, SiC, Cr₃C₂,Al₂O₃, ZrO₂—Y, TiN, TiB so as to improve the anti-abrasiveness andhexagonal BN, MOS₂, Cr₂O₃, WS₂ and BaZrO₄ so as to improve thelubricity.

The coating layers 119 are formed in a following manner. Morespecifically, mixing powder of Ti (about 10%) for assuring electricconductivity, powder of TiC (about 40%) as an example of the ceramicshaving anti-abrasiveness and powder of hexagonal BN (about 50%) as anexample of a lubricant material having lubricity; and compressing andmolding them for example are carried out to form a molded body electrode121 (see FIG. 4). This molded body electrode 121 is preferably subjectto heat treatment after compression and molding so as to be temporarilysintered at temperatures below the sintering temperature.

After compressing and molding the molded body electrode 121 as mentionedabove, or after compressing and temporary sintering, in a condition thatsmall spaces are kept between the molded body electrode 121 and theshaft portions 103 and 111 of the variable stator vanes 101, as rotatingthe shaft portions 103 and 111 of the variable stator vanes 101, apulsing electric discharge is generated therebetween in a processingtank (not shown) of an electric spark machine (not shown) and thenelectrode constituents of the molded body electrode 121 or compoundscombined in the electric discharge atmosphere move to the shaft portions103 and 111 as basic materials and are deposited on the surfaces of theshaft portions 103 and 111 to form the coating layers 119. The coatinglayers 119 contain TiC and hexagonal BN and the anti-abrasiveness andthe lubricity are improved.

Meanwhile, as the electrode 121, a molded body electrode wherein powderof Ti and powder of hexagonal BN are mixed, compressed and molded, or anelectrode wherein the appropriate heat treatment for temporary sinteringis carried out, can be used. In these cases, if a pulsing electricdischarge happens between the molded body electrode 121 and the shaftportions 103 and 111, any carbides in the processing liquid in theprocessing tank of the electric spark machine and a part of Ti arecombined to form TiC as a compound.

Further, the electrode 121 may be molded by slurry pouring, MIM (MetalInjection molding),spray forming (forming by spraying) or such.

As mentioned above, because the surfaces of the shaft portions 103 and111 as the base material are made to be instantaneously fused andsolidified by means of the pulsing electric discharge when the coatinglayers 119 are formed on the shaft portions 103 and 111, the coatinglayers 119 lead to that diffusion-penetration layers 119A in which TiCand hexagonal BN from the electrode material diffuse and penetrate toseveral, m depth from the base material surface are formed and depositlayers 119B in which fine particles of the electrode material aredeposited on the diffusion-penetration layers 119A are formed.

As being understood from the above description, in the presentembodiment, because it is constituted to provide the coating layers 119having anti-abrasiveness and lubricity for the shaft portions 103 and111 of the variable stator vanes 101 provided in the compressor of thegas turbine engine, swing of the variable stator vanes 101 is capable ofbeing smoothly carried out and the anti-abrasiveness of the shaftportions 103 and 111 is improved so that an exchange life of thevariable stator vanes 101 comes to be a long life, thereby theaforementioned prior problem can be solved.

More specifically, because it is provided with the coating layerscontaining ceramics having anti-lubricity and the lubricating materialon the peripheral surfaces of the shaft portions provided at thevariable vanes for regulating the fluid, the anti-abrasiveness and thelubricity of the shaft portions are improved and the life of the shaftportions is further improved.

Moreover, in the shaft structure of the variable vanes for regulatingthe fluid, because the coating layers contain ceramics such as cBN, TiC,WC, SiC, Cr₃C₂, Al₂O₃, ZrO₂—Y, TiN, TiB and a lubricating material suchas hexagonal BN, MOS₂, Cr₂O₃, WS₂ and BaZrO₄, the anti-abrasiveness andthe lubricity are improved.

Moreover, because a pulsing electric discharge is generated between anelectrode containing ceramics such as cBN, TiC, WC, SiC, Cr₃C₂, Al₂O₃,ZrO₂—Y, TiN, TiB and a lubricating material such as hexagonal BN, MOS₂,Cr₂O₃, WS₂ and BaZrO₄ and the shaft portions of the variable vanes forregulating the fluid, by forming the coating composed of the electrodeconstituents or the compounds combined in the electric dischargeatmosphere on the shaft portions, the coating layers havinganti-abrasiveness and lubricity are formed so that the anti-abrasivenessand the lubricity of the shaft portions are improved and the life of theshaft portions is further improved.

By the way, the present invention is not limited to the embodiments suchas aforementioned, and for example the coating layers 119 may be appliedto portions of rotation shafts of swingable vanes (variable vanes) forregulating an impact angle of exhaust gas to vanes of turbine wheels bychanging the flow direction of the exhaust gas in a turbo charger whichuses the exhaust gas from an engine to compress an air to be supplied tothe engine.

If the coating layers 119 are applied to the portions of the rotationshafts of the swingable vanes in the turbo charger, anti-abrasiveness ofthe rotation shafts is improved so as to be long life as well as swingof the vanes can be smoothly carried out, thereby a similar effect isgiven.

Meanwhile, in the aforementioned description, though it is describedthat Ti, TiC and hexagonal BN are contained as constituents of thecoating layers 119, as the ceramics, instead of TiC, TiN, TiB and suchmaybe applied. More specifically, proper selection may be allowable astaking anti-abrasiveness, lubricity and a degree of hardening bycombining with carbon into consideration.

The contents of Japanese Patent Application No. 2003-166992 (filed Jun.11, 2003) and Japanese Patent Application No. 2003-167030 (filed Jun.11, 2003) are incorporated in this specification of the presentapplication by reference in its entirety.

Moreover, the present invention is not limited to the aforementionedembodiments of the invention and will be embodied in other versions byappropriate modifications.

1-20. (canceled)
 21. A rotation member applied to and rotating in ahousing, comprising: an engaging portion rotatably supported by thehousing; and a coating covering the engaging portion and including oneor more wear-resistant materials selected from the group consisting ofSi, cubic BN, TiC, WC, SiC, Cr₃C₂, ZrO₂—Y and TiB, the coating beingdeposited from a tool electrode including the wear-resistant materialsby processing the engaging portion as a workpiece with electric sparkmachining.
 22. The rotation member of claim 21, wherein the coatingincludes one or more solid lubricants selected from the group consistingof hexagonal BN, MoS₂, Cr₂O₃, WS₂ and BaZrO₄.
 23. The rotation member ofclaim 21, wherein the coating consists essentially of one or morewear-resistant materials selected from the group consisting of Si, cubicBN, TiC, WC, SiC, Cr₃C₂, ZrO₂—Y and TiB and one or more solid lubricantsselected from the group consisting of hexagonal BN, MoS₂, Cr₂O₃, WS₂ andBaZrO₄.
 24. The rotation member of claim 21,wherein the electric sparkmachining is carried out with rotating the rotation member.
 25. Therotation member of claim 21, wherein the engaging portion includes agroove configured to pool a lubrication liquid.
 26. A housing forrotatably supporting a rotation member, comprising: a supporting portionconfigured to rotatably support the rotation member; and a coatingcovering the bearing and including one or more wear-resistant materialsselected from the group consisting of Si, cubic BN, TiC, WC, SiC, Cr₃C₂,ZrO₂—Y and TiB, the coating being deposited from a tool electrodeincluding the wear-resistant material by processing the bearing as aworkpiece with electric spark machining.
 27. The housing of claim 26,wherein the coating includes one or more solid lubricants selected fromthe group consisting of hexagonal BN, MoS₂, Cr₂O₃, WS₂ and BaZrO₄. 28.The housing of claim 26, wherein the coating consists essentially of oneor more wear-resistant materials selected from the group consisting ofSi, cubic BN, TiC, WC, SiC, Cr₃C₂, ZrO₂—Y and TiB and one or more solidlubricants selected from the group consisting of hexagonal BN, MoS₂,Cr₂O₃, WS₂ and BaZrO₄.
 29. The housing of claim 26, wherein the bearingincludes a groove configured to pool a lubrication liquid.
 30. A gearbox comprising of the rotation member of claim
 21. 31. A gear boxcomprising the housing of claim
 26. 32. A shaft structure of variablevanes for regulating a fluid, comprising the rotation member of claim21.
 33. A shaft structure of variable vanes for regulating a fluid,comprising the housing of claim
 26. 34. A method for a surface treatmentof a shaft or a bearing, comprising: setting a tool electrode includingone or more materials selected from the group consisting of Ti, Si,cubic BN, TiC, WC, SiC, Cr₃C₂, Al₂O₃, ZrO₂—Y, TiN, TiB, hexagonal BN,MoS₂, Cr₂O₃, WS₂ and BaZrO₄; setting the shaft or the bearing as aworkpiece; and forming a coating deposited from the tool electrode onthe workpiece by electric spark machining.
 35. The method of claim 34,wherein the forming includes rotation of the workpiece.
 36. The methodof claim 34,wherein the tool electrode includes one or morewear-resistant materials selected from the group consisting of Ti, Si,cubic BN, TiC, WC, SiC, Cr₃C₂, Al₂O₃, ZrO₂—Y, TiN and TiB and one ormore solid lubricants selected from the group consisting of hexagonalBN, MoS₂, Cr₂O₃, WS₂ and BaZrO₄.
 37. The method of claim 34, furthercomprising: molding the tool electrode from powder of including one ormore wear-resistant materials selected from the group consisting of Ti,Si, cubic BN, TiC, WC, SiC, Cr₃C₂, Al₂O₃, ZrO₂—Y, TiN and TiB and one ormore solid lubricants selected from the group consisting of hexagonalBN, MoS₂, Cr₂O₃, WS₂ and BaZrO₄ by compressing.
 38. The method of claim34, wherein the forming is carried out in an electrically insulatingliquid or an electrically insulating gas at an atmospheric pressure. 39.A shaft processed with a surface treatment by the method of claim 34.40. A bearing processed with a surface treatment by the method of claim34.
 41. A gear box comprising the shaft of claim
 39. 42. A gear boxcomprising the bearing of claim
 40. 43. A shaft structure of variablevanes for regulating a fluid, comprising of the shaft of claim
 39. 44. Ashaft structure of variable vanes for regulating a fluid, comprising thebearing of claim 40.